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Population change map

Source: vignettes/a01_Interactive-map.Rmd
a01_Interactive-map.Rmd

Use the interactive map below to check population changes. Zoom in to see where Podocnemis unifilis is Endangered based on IUCN Red List criteria - A3bd.

  • Overall Podocnemis unifilis is Endangered (“Em perigo” / “En peligro”) based on future population size reduction criteria - A3bd.
    Within 3 generations (35 years) the adult female population is predicted to decline by 53.5% in the future (25 and 75% quantile range: 57 - 50.2 % decline).

Map

If you find any errors (e.g. points where Podocnemis unifilis does not occur, points where species is “Endangered” but populations are increasing etc) please raise an issue at: https://github.com/darrennorris/TACAR/issues .

  • When you zoom in you will see shaded points.
    The points are brown where populations are predicted to decline by 50% or more within 3 generations (35 years). Brown points therefore represent rivers where the species is Endangered (“Em perigo” / “En peligro”), following the IUCN Red List population size reduction criteria - A3bd (https://www.iucnredlist.org/about/faqs).

  • The points follow rivers mapped by remote sensing. This standardized global scale mapping comes from Grill et al 2019, Free-flowing Rivers: https://doi.org/10.1038/s41586-019-1111-9. The points are locations along rivers selected to represent where Podocnemis unifilis females are likely to nest and that are likely to be accessible to people by boat. To facilitate online viewing the mapped points are a subset at intervals of approximately 10 kilometers.

  • Due to the number of points, the map can become slow to respond when you zoom in.
    If this happens, zoom out to a level showing fewer points and you can pan around the map to find the area of interest. Then zoom in again to check the coloured points.

  • The population reductions are conservative (best-case) estimates.
    Endangered (A3bd), is threfore a precautionary IUCN Red List assessment.

    • Important threats are not included (e.g. land use change Zalles et. al. 2021).
    • Losses are potentially buffered by an overly generous 20% ceiling to increases in unaccesible/unhunted populations.
    • Population projections use the earliest likely breeding age. The age at first reproduction was set to 5 years (Norris et. al. 2019).
    • Hunting of adult females was limited to 10% per year in the most pessimistic scenarios.
    • Hunting accessibility was limited to a distance of 48 km from locations with a human population density of 5 or more people per km2. This will underestimate impacts associated with threats such as large scale harvest around urban areas (Chaves et. al. 2021, Tregidgo et. al. 2017).

Methods

The analysis is developed here: https://github.com/darrennorris/TACAR. The workflow, data and associated R code is available here: https://darrennorris.github.io/TACAR/articles/Matrix-population-model-projections.html

The methods used are an extension of Norris et. al. 2019 that includes:

  • Stochastic population projections.
  • Future impacts to populations caused by human acessibility (hunting) and actions that reduce river connectivity.

References

Bienvenu F, Legendre S. 2015. A new approach to the generation time in matrix population models. The American Naturalist. 185(6):834-43. https://doi.org/10.1086/681104.

Chaves, W.A., Valle, D., Tavares, A.S., Morcatty, T.Q. and Wilcove, D.S. 2021. Impacts of rural to urban migration, urbanization, and generational change on consumption of wild animals in the Amazon. Conservation Biology, 35: 1186-1197. https://doi.org/10.1111/cobi.13663

IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K.

IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. IUCN, Gland, Switzerland and Cambridge, UK. Available at www.iucnredlist.org/technical-documents/categories-and-criteria

IUCN. 2024. Guidelines for Using the IUCN Red List Categories and Criteria. Version 16. Prepared by the Standards and Petitions Committee. Downloadable from https://www.iucnredlist.org/documents/RedListGuidelines.pdf.

Jones OR, Barks P, Stott IM, James TD, Levin SC, Petry WK, Capdevila P, Che-Castaldo J, Jackson J, Römer G, Schuette C, Thomas CC, Salguero-Gómez R. 2022. Rcompadre and Rage - two R packages to facilitate the use of the COMPADRE and COMADRE databases and calculation of life history traits from matrix population models. Methods in Ecology and Evolution, 13, 770-781. doi:10.1111/2041-210X.13792.

Norris D, Peres CA, Michalski F, Gibbs JP. 2019. Prospects for freshwater turtle population recovery are catalyzed by pan-Amazonian community-based management. Biological Conservation. 233:51-60. https://doi.org/10.1016/j.biocon.2019.02.022

Stott, I. popdemo vignette: https://cran.r-project.org/web/packages/popdemo/vignettes/popdemo.html

Stott, I., Hodgson, D.J. and Townley, S. 2012. popdemo: an R package for population demography using projection matrix analysis. Methods in Ecology and Evolution, 3: 797-802. https://doi.org/10.1111/j.2041-210X.2012.00222.x

Stubben, C., & Milligan, B. 2007. Estimating and Analyzing Demographic Models Using the popbio Package in R. Journal of Statistical Software, 22(11), 1–23. https://doi.org/10.18637/jss.v022.i11

Tregidgo, D. J., Barlow, J., Pompeu, P. S., de Almeida Rocha, M., & Parry, L. 2017. Rainforest metropolis casts 1,000-km defaunation shadow. Proceedings of the National Academy of Sciences, 114(32), 8655-8659. https://doi.org/10.1073/pnas.161449911

Zalles V, Hansen Matthew C, Potapov Peter V, Parker D, et al. 2021. Rapid expansion of human impact on natural land in South America since 1985. Science Advances, 7: eabg1620. https://doi.org/10.1126/sciadv.abg1620